1. Field of the Invention
The present invention relates to monolithic block-shaped wall construction units, such as masonry blocks, and more specifically to an improved stackable wall and column construction units adapted for use in constructing dry-stackable structures.
2. Discussion of Related Art Including Information Disclosed Under 37 CFR §§1.97, 1.98
The art of building dry stack stone walls is ancient and therefore highly developed. Even so, due to the high cost and difficulty of constructing walls of quarried stone or block, cast cementitious blocks long ago replaced quarried stone as a preferred material in many applications.
Cast blocks typically have a uniform size and shape, include at least one cavity, and frequently permit physical interlocking, either vertically or horizontally, with physical elements frequently integrally formed in the blocks. Such interlocking designs facilitate rapid assembly and proper alignment during fabrication. They also permit assembly without mortar, so that some designs of cast blocks may be employed for temporary walls that can be easily disassembled.
Dry stacked walls constructed of cast blocks may rely exclusively on the mass of the stacked blocks to maintain alignment and stability. However, mortarless cementitious cast block walls intended for permanent use usually require additional stability. Accordingly, many designs permit mortar or reinforced concrete to be poured or injected into and to fill gaps and aligned vertical and horizontal openings in the blocks.
However, along with their advantages, the known cast blocks also have many disadvantages, including: difficulty in converting the wall units into end or corner units; lateral instability; vulnerability of exposed mortar to chemical or environmental degradation; expansion and contraction of mortar, causing cracking and separation of blocks; difficulty in constructing curved configurations; and vulnerability of broad flat surfaces to defacement and graffiti.
Accordingly, the inventor of the present invention devised a mason wall cementitious building block system that is the described in U.S. Pat. No. 6,205,735, which is incorporated in its entirety by reference herein. The system disclosed therein comprises a wall and a corner unit making up a lightweight dry-stackable block unit system. Both wall units and corner/end units connect one to another in an interlocking fashion. The unit shapes and the method of assembling walls using such units provided several solutions to the problems then present in the prior art.
However, the improved block of the '735 patent was adapted for use with steel reinforcement bar and poured in concrete for structural stability and as a means to resist displacement of the stacked stones. This made any wall built with the inventive system necessarily permanent and essentially impossible to change or modify after and during construction without damaging the block material. Additionally, wall construction required labor skilled in the masonry and concrete trades.
The present invention represents a dramatic improvement over the technology described in the '735 by providing a simplified block that nevertheless provides equivalent structural integrity when dry stacked, but requires no interlocking pieces. Further, the inventive system employs a novel hardware system that facilitates rapid dry stack construction while providing significantly enhanced strength and stability over prior art designs.